(Adapted from the Applicant's Abstract) The Mouse Core for this SCOR proposal is built on and integrated with four existing Cores or Services of the Molecular Cardiology Research Institute at New England Medical Center and Tufts University School of Medicine. These four components include: 1) the MCRI Transgenic Mouse Facility 2) The Mouse Tissue Histology Service, 3) the MCRI Mouse Physiology Core and 4) the MCRI Cell Culture Facility. The Mouse Core serves and is closely integrated with Project s 3, 4 and 5 of this SCOR proposal and details regarding experimental interactions may be found in these 3 projects. Descriptions of each of the four MCRI components upon which the SCOR Mouse Core is built follow. MCRI Transgenic Facility (Janis Lem, Ph.D., Director): The MCRI Transgenic facility is housed in a newly constructed 2500 square foot that houses the capabilities to produce both standard transgenic mice by pronuclear microinjection and knockout/knockin mice by blastocyst injection. Contained within the facility is dedicated animal housing, a microinjection lab, a molecular biology lab, and a tissue culture room, along with a cold room, conference room, and office space. The animal room has a capacity of -500 state-of-the-art self-ventilated cages (3,500 mice) to house stud and vasectomized males and donor and recipient female mice used in the production of transgenic and knockout/knockin mice. Dr. Mary Ellenberger, DVM, oversees the care and maintenance of animals, fully in accordance with NIH and institutional guidelines. The investigators Institution is accredited by AAALAC and has current PHS Animal Welfare Assurance.